Table 1

Cytotoxicity activity (IC50) in ng/mL of BL22 and mutant immunotoxins toward various cell lines

CD22-positive cell line (Burkitt's lymphoma)
CD-22-negative cell line
DaudiCA46RajiHUT-102*L540
BL222.78 ± 0.110.85 ± 0.042.63 ± 0.24>2,000>10,000
HA220.46 ± 0.020.24 ± 0.011.02 ± 0.09>2,000>10,000
HA22 (R490A)0.18 ± 0.010.18 ± 0.020.27 ± 0.02∼2,000>10,000
  • NOTE. Cytotoxicity data are given as IC50's, which are the concentrations of immunotoxin that cause a 50% inhibition in protein synthesis compared with controls after incubation with cells for 20 hours. Means values of three experiments ± SD are shown.

  • * CD22-negative, human T-cell lymphotrophic virus-1–positive T-cell lymphomas.

  • CD22-negative, CD30-positive Hodgkin's lymphomas.